Proanthocyanidins from Lotus pedunculatus

A range of flavanols and proanthocyanidin dimers were isolated and identified from Lotus pedunculatus. The more abundant polymeric proanthocyanidins were also isolated and their chemical constitution studied by C-13 NMR and by acid-catalysed degradation in the presence of excess phloroglucinol. These results showed the polymers to be highly heterogeneous, with catechin, epicatechin, gallocatechin and epigallocatechin all being constituent components of both the extenders as well as the terminating units; Epigallocatechin was the most abundant extension unit and catechin the more common terminating flavanoid. The average molecular size of the polymers was estimated by C-13 NMR to be ca eight flavanoid units and there was spectroscopic and chemical evidence to indicate that a small portion of these units were glycosylated. (C) 1997 Elsevier Science Ltd. All rights reserved.